Reenforced floor construction



Apr. 3, 1923.-

' 1,450,187 K. R. SCHUSTER REENFORCED FLOOR CONSTRUCTION Filed Jan. 16, 1919 2 sheets-sheet 1 MlVE/VTOR I 'QfZ/LZ G a B 3 Apr. 3, 1923.

. 1,450,187 K. R. SCHUSTER REENFORCED FLOOR CONSTRUCTION Filed Jan. 16, 1919 '2 sheets-sheet 2 INVENTOR Patented Apr. 3, 1923.

UNITED STATES resale? KARL R. SCHUSTER, OF-BROOKLYN', NEW YORK.

REENFORCED FLOOR CONSTRUCTION.

Application filed January 16, 1919. Serial 271,358.

To all whom it may concern:

Be it known that I, KARL R. SoHUs'rnR, a resident of the city of New York, borough of Brooklyn, county of Kings, and State of New York, have invented a certain new and useful Reenforced Floor Construction, of which the following is a specification.

This invention is a reenforced floor construction, and it pertains, more particularly, to that type of fioor structures wherein a composite plate. approximately square in form is supported on the several sides thereof, in contra-distinction to flat slabs, so called, embodying a monolithic structure supported at the corners only of the slab through the employment of subjacent columns.

In composite floor structures of the type wherein an approximately square plate is supported by subjacent walls or beams on the several sides thereof, it has been assumed, almost universally, that the greatest bending moment (B M) is located centrally of the square plate and parallel to the marginal lines at the sides thereof. In the course of my engineering work and as the result of experiments I have found that the lines of fracture and therefore also the greatest B Ms in an approximately square plate are diagonal, running from the corners of said plate, or substantially from the corners,'to substantially the central point of the plate, and, further, that the reaction upon the supported marginal portions of the plate is not uniform. Accordingly, my experience and experiments have shown that there is actually: a condition wherein the marginal portions of the composite plate buckle upwardly, as graphically depicted in Fig. 1 of the drawings, and this establishes conclusively that the greatest reaction is upon the marginal supports of the approximately square plate at or near the corners thereof, as a result of which the bending moment (B M) of the supporting beams is considerably reduced. Such upward buckling at the marginal portions of the plate has the effect of reversing the lines of stresses ,in the plates, by transferring the compression to the bottom chord and by changing the tension to the top chord of the plate.

The salient feature of my invention resides in an organization and location of the steel rods constituting the reinforcement so as to scription taken in minimize the quantity of steel required to stresses at the several corners'of such plate, l

thereby attaining maximum. efficiency with an economical cost of construction.

Other functions and advantages of the invention will appear from the following deconnection with the drawings, wherein 1 I Fig. 1 is a perspective view illustrating an approximately square plate supported by beams along the marginal portions thereof and showing graphically the diagonal lines of fracture and the upward buckling at the marginal portions due to excessive loading of the plate. V

Fig. 2 is a plan view of a square form of plate illustrating'the disposition of the steel rods.

Figs. 3, 4, 5 and 6 are plan views of other composite square plates'illustrating equivalent arrangements of the belt courses of rods in accordance with this invention.

Figs. 7 8, 9 and 10 are cross sections on the lines 77 of Fig. 6, 88 of Fig. 4, 99 of Fig. 3, and 10l0 of Fig. 5. i

Fig. 11 is a plan view'of a rectangular m composite plate of I certain dimensions wherein is incorporated courses of steel rods for reinforcing the composite structure in. accordance with the present invention.

The means for reinforcing a flatcomposite plate in accordance with the present invention possesses marked utility in plates which are square in form, or approximately square; that is to say, inplates the length of the sides ofwhich are equal, or in those J composite plates wherein there is or may be a variation in the ratio of approximately 1:1.5. 7

As shown in Fig. 1, the composite plate A is square in form and supported by walls or beams at the several sides thereof, and in the manner depicted diagrammatically in Fig. 1. Said slab iskcomposed ofroncrete, or concrete and tile, and is crosswise reenforced, for which'purpose I use two series of main rods indicated at B, C, the rods B of one series running in onedirection and parallel to each other, whereas the rods C of the other series run at right angles to rods B and may thus be said torun in an opposite or crosswise direction, parallel to each other. T he rods of the two series thus intersect, and they are spaced equidistantly, for which reason the rods are arranged advantageously for the utilization of tile blocks in the construction or installation of the floor structure. I p

In the present invention the plate is essentially crosswise reenforced by belt courses of rods extending at right angles, for the rea son that such a reenforced plate is equally strong in all directions, and is economical in 'the use of steel, and economical also in the quantity of concrete forthe reason that tile blocks may in part replace to a'certain extent a proportionate quantity of the concrete without sacrificing strength, particularly should thetile blocks be interlocked to the concrete beams making up agrid of concrete as disclosed in my prior Patent No. 1,134,161 although it is to be distinctly understood that the present invention is'not restrictedto the utilization 0t tile blocks in interlocking relation to the concretebeams, nor is it, in fact, limited to the use of any blocks, of tile or otherwise.

The beltc'ourses' of rods B C are in the lower chord of the plate and act as tension members for taking care of the stresses under the load imposed upon the plate.

In addition to the specified crossing rods B, G, I employ additional courses of rods D, E in the several corners of the plate and in the lower chord thereof! Such additional reinforcement DE is in each corner of the plate, and comprises two series of rods shorter than the main rods B, C. the short rods D of one series being parallel to the main rods B, whereas the other short rods E are parallel to the other main rods C. The short additional rods D E cover an area square in form and crossing the prospective lines of fracture extending diagonally from the center of the plate to the four corners thereof, a desired number of rods D E being employed in each group in the respective corners of the plate so that each group of shorter crossing rods D E may be said to extend from the corner of the plate inwardly toward the center thereof. The shorter rods D E are parallel to two sides of the square plate, and the several groups of said short rods leave portions of the plate. at the several sides and in the middle region thereof. reenforced only by the main belt courses of rods C.

Said main rodsstiifen the plate uniformh in all' directions, {whereas the groups of shorter rodsD in the corners of the plate operate to strengthenlthe latter against rup ture along the diagonal lines of fracture because saidrods cross the diagonal lines, and said shorter rods operate, also, to strengthen theplate againstfthe greater stresses oi: the

vertical shear whichoccurs at or near the corners due to the greater react-ion 011 the supports near or at said corners.

In the plate of Figs. 3 and 9 the main rods B C and corner groups of shorter rods 1) E are employed as in Fig. 2, and in addition thereto other rods F are employed in the top chord of the composite plate, and in the middleregion of the several side portions of said plate. Said rods F in the top chord are parallel to the main rods B, C, and they extend between the shorter rods D E of the corner groups so that the end portions of the top rods F are in overlapping relation to certain rods of the corner groups. The additional rods F in the top chord of the plate take care of the tension occurring in the middle of the several side portions of the plate due to the imposition of a high load upon said plate. In said Figs. 3 and}? the main rods B C and groups of corner rods D E positioned in the lower chord of the plate are indicated by dotted lines, whereas the additional rods F located in the top chord of said plate are shown in full lines, although it should be understood that all the rods are embedded at suitable depths in the material composing the plate.

The composite plate illustrated in Figs. 4c and 8 embodies the generic features of the crosswise and corner reinforcements shown.

and described in connection with Fi s. 3 and 9, for the reasonthat the main rods B G extend throughout the entire area of the plate, the corner groups of shorter rods D, E extend across the diagonal lines of fracture, and the additional rods F are used at the several marginal portions or" the plate and in the upper chord thereof and between the corner groups of shorter rods. In this form of the invention, there is used a sutticient number of the shorter rods D E to extend from corner to corner of the plate, the lines of such shorter rods crossing the diagonal lines of fracture so that one series of the shorter rods in one diagonal line from two corners cross or intersect with the other series of similar rods extending diagonally between the two remaining corners, the two diagonal series presenting the form of a cross with triangular spaces in the middle portions at the several sides of the plate, at which regions the additionalrods F are used in the top chord of said plate.

A further embodiment of the plate stiffeued with rods is shown in Figs. 5 and 10, wherein the reinforcement in the several corners and in the marginal portions is obtained by resorting to the use of heavier rods, the latter acting to strengthen the plate against fracture on diagonal lines between the corners and atthesame time to stiffen the plate against the greater vertical shear near said corners. A To this end, the crossing rods B, {lextending tl1rougli the.plateiin two directions are of predetermined size in cross section, whereas the other rods B C are considerably heavier or larger in cross section. The fheavier rods B C extend across each other in the corners of the plate and run parallel to the marginal portions thereof, said rods B U crossing the diagonal lines of fracture and so operate to stiffen the plate in a manner to preclude fracture along diagonaldines running to the corners and they operate. also, to preclude upward buckling of the plate atthe marginal portions thereof. The lighter rods B C between the beltcourses of heavier rods B C, and all of said rods are in the lower chord of the plate.

The effect of increasing the cross section of metal in the slab can be attained either by using rods of heavier cross section, as at B C in Figs. 5 and 10, or, obviously, it

can be obtained by grouping rods of lighter cross section closer together, as is well known to those skilled in the art.

A further embodiment of the invention is shown in Figs. 6 and 7 wherein the lighter rods B C and heavier rods B G are positioned in crossing order, with the heavier rods B C extending across the diagonal lines of fracture and in the corners of the plate and in the'marginal portions thereof, all for the purposes herein specified. In this form, however, the heavier bars B C in the corners and at the margins are bent upwardly at Z) 0, see Fig. 7, so as to extend at C through the middle portions of the plate and in the marginal portions thereof, said upwardly positioned portions C of the heavier rods B G being in the top chord for taking care of the tension occurring in the upper chord of the plate at the marginal portions.

The composite plates of Figs. 2, 8, 4c, 5 and 6 are square inform, but in Fig. 11 there is shown a plate rectangular in form the ratio of the short side to the long side of which equals 1:1.5, although it is to be understood that the reinforcing means herein disclosed may be used in plates of any shape approximating a square to that resembling a rectangle, each shape having the ratio of sides of 1: approximately 1.5. The plate of Fig. 11 includes the crossing main rods B C, the heavier rods B C in the marginal and corner portions as in Figs. 5 and 6, and additional rods G G. The rods B C B C are in the lower chord of the plate, whereas the rods G G are in the top chord, said rods G G being parallel to rods B C and extending along the marginal portions of the plate, one series on each side thereof.

Although I have shown and described the invention as especially designed for floor constructions, it is to be distinctly understood that the principle of the invention is applicable to other structures, for the reason sible lines of fracture extending diagonally y from the central portion of the plate to the respective corners thereof, embodying two series of main rods in thelower chord of the plate, with the rods of one series crossing the rods of the other series and with the rods of each series spaced equi-dist'antly apart, groups of additional rods positioned 111 the several corner portions of the plate.

and extending crosswise of the possible diagonal lines of fracture and operating to take care of thevertical shear occurring at the corners of the plate, and other rods in the upper chord of the plate and extending along the marginal portions thereof between the groups of additional corner rods.

2. A floor construction 'wherein'a 'composite plate is supported on'the marginal portions thereof and which plate has a tendency to develop under excessive loading possible lines of fracture extending diagonallv from the central portion of the plate to the respective corners thereof, embodying two series of main rods in the lower chord of the plate, with the rods of one series crossing the rods of the other series and with the rods of each series spaced equidistantly apart, rods in the corner portions of said plate, parallel to the marginal portions thereof, and extending across the possible diagonal lines of fracture in the plate, the. aggregate cross section of the corner rods being in excess of the main rods in the body of the plate, and rods in the upper chord of the plate, between the corner rods thereof and extending parallel to the marginal portions of the plate.

3. A floor construction wherein a COII1.

series of main rods in the lower chord of the plate, with the rods of one series crossingv the rods of the other series and with the rods of each series spaced equidistantly apart, 9

groups of short corner rods, one group on each corner, positioned parallel to the marginal portions of the plate and extending crosswise of the, diagonal lines of possible fracture, and other short rods in the upper chord of the plate and at the marginal portions thereof, said last mentioned rods being intermediate the rods" composing the groups of corner rods.

4. A floor construction wherein a composite plate tends to develop lines of fracture extending diagonally fromnie corners to the middle region of the plate embodying two series of main rods extending Substantially throughout the entire area of said plate, with the rods of one series crossing the rods of the other .series, and shorter rods within the plate and in the area s thereof extending substantially from the middle region to the diagonal corners of saidplate, said shorter rods crossing the undeveloped diagonal lines of fracture.

5. A floor construction wherein a C0111- posite plate tends to develop lines of fracture QXtQIlCllDg diagonally from the corners to the middle region of the plate, embodying two series of main rods extending substantially throughout the entire area of said plate, with the rods of" one series crossing the rods oi the other series. said main rods being in the lower chord of'the plate, and groups of additional rods, one group in each corner of the plate,'-said groups of rods extending substantially from the middle region t'oth'e corners of the'plateand with said additional rods'crossing the undeveloped diagonal lines ot' fracture. I

6. A floor construction wherein a'com'pos ite plate tends to develop lines of fracture extending diagonally from the corners to the middle region of the plate, embodying two series or main rods extending substanand said additional metal crossing the un-' developed diagonal lines of fracture, said two series of main rods and the additional metal in the corners of said plate being in the lower chord of the plate.

7. A floor construction wherein a composite plate is supported at the margin thereof and which plate tends under load stresses to develop lines of fracture extending diagonally from the corners to the mid dle region, embodying two series of rods extendinp; substantially throughout the area of the plate, with the rods of one series crossing the rods of the other series, and with said main rods in the lower chord of the plate, and groups 01 additional rods positioned in the corners of the plate and extending substantially from the middle region to the corners of the plate, said additional rods extending crosswise of the undeveloped lines of diagonal fracture and with aggregate area in cross section of said additional rods exceeding the cross sectional area of said main rods, wherebythe additional rods take care of the vertical shear in the corners of the plate.

In testimony whereof I have hereunto subscribed my name.

KARL R. SCYUSTER. 

